System and method for synchronizing integrated circuit chips

ABSTRACT

A system and method for synchronizing multiple integrated circuit (IC) chips for an input device having a display device integrated with a capacitive sensing device. A first one of the IC chips is a master IC chip and a second one of the IC chips is a slave IC chip. The master IC chip is configured to transmit synchronization signals to and from the slave IC chip, such that capacitive frames are acquired by each of the IC chips at substantially the same time, the initiation of the sensing signals is synchronized for each of the IC chips and the clock signals of the slave IC chips are synchronized with the clock signal of the master IC chip.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit of U.S. provisional patent applicationSer. No. 62/722,794, filed Aug. 24, 2018, entitled “SYSTEM AND METHODFOR SYNCHRONIZING INTEGRATED CIRCUIT CHIPS,” which is hereinincorporated by reference.

BACKGROUND Field

Embodiments disclosed herein generally relate to electronic devices, andmore specifically, to synchronizing integrated circuit chips.

Description of the Related Art

Input devices including proximity sensor devices may be used in avariety of electronic systems. A proximity sensor device may include asensing region, demarked by a surface, in which the proximity sensordevice determines the presence, location, force and/or motion of one ormore input objects. Proximity sensor devices may be used to provideinterfaces for the electronic system. For example, proximity sensordevices may be used as input devices for larger computing systems, suchas touchpads integrated in, or peripheral to, notebook or desktopcomputers. Proximity sensor devices may also often be used in smallercomputing systems, such as touch screens integrated in cellular phonesor vehicles (e.g., automobiles).

SUMMARY

In one embodiment, an input device comprises a plurality of sensorelectrodes, a master integrated circuit (IC) chip, and a first slave ICchip. The master integrated circuit (IC) chip is communicatively coupledto a plurality of sensor electrodes and is configured to generate avertical timing signal and a horizontal timing signal, and initiateacquisition of a first capacitive frame based on at least one of thevertical timing signal and the horizontal timing signal by driving theplurality of sensor electrodes with a first sensing signal comprisingone or more sensing bursts. The first slave IC chip is communicativelycoupled with the master IC chip and to the plurality of sensorelectrodes, and is configured to receive the vertical timing signal andthe horizontal timing signal from the master IC chip, and initiateacquisition of a second capacitive frame based on at least one of thevertical timing signal and the horizontal timing signal by driving theplurality of sensor electrodes with a second sensing signal comprisingone or more sensing bursts.

In one embodiment, a method for synchronizing IC chips comprisesgenerating, with a master IC chip, a vertical timing signal and ahorizontal timing signal, transmitting the vertical timing signal andthe horizontal timing signal from the master IC chip to a slave IC chip,initiating acquisition of first sensing measurements by the master ICchip based on at least one of the vertical timing signal and thehorizontal timing signal, and initiating acquisition of second sensingmeasurements by the slave IC chip based on at least one of the verticaltiming signal and the horizontal timing signal.

In one embodiment, a processing system for a display device having anintegrated capacitive sensing device comprises a master IC chipcommunicatively coupled to a plurality of sensor electrodes, and a slaveIC chip. The master IC chip is configured to generate a vertical timingsignal and a horizontal timing signal, and initiate acquisition of afirst capacitive frame based on at least one of the vertical timingsignal and the horizontal timing signal by driving the plurality ofsensor electrodes with a first sensing signal corresponding to one ormore sensing bursts. The slave IC chip is communicatively coupled withthe master IC chip and to the plurality of sensor electrodes, and isconfigured to receive the vertical timing signal and the horizontaltiming signal from the master IC chip, and initiate acquisition of asecond capacitive frame based on at least one of the vertical timingsignal and the horizontal timing signal by driving the plurality ofsensor electrodes with a second sensing signal corresponding to one ormore sensing bursts.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentdisclosure can be understood in detail, a more particular description ofthe disclosure, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlyexemplary embodiments, and are therefore not to be considered limitingof inventive scope, as the disclosure may admit to other equallyeffective embodiments.

FIG. 1 is a schematic block diagram of an input device, according to oneor more embodiments.

FIG. 2 illustrates an example display device and sensor device,according to one or more embodiments.

FIG. 3 illustrates multi-chip configuration for driving a display panel,according to one or more embodiments.

FIG. 4 is a block diagram of a synchronization device, according to oneor more embodiments.

FIG. 5A illustrates various signal connections, according to one or moreembodiments.

FIG. 5B a system for generating a synchronization signal, according toone or more embodiments.

FIGS. 6A, 6B and 6C illustrate a block diagram for synchronizing chips,according to one or more embodiments.

FIGS. 7A-1, 7A-2, 7A-3, 7A-4, 7B-1, 7B-2, 7B-3 and 7B-4 illustrate ablock diagram for synchronizing chips, according to one or moreembodiments.

FIGS. 8A and 8B illustrate a block diagram of signal pathways, accordingto one or more embodiments.

FIG. 9 illustrates a synchronization signal, according to one or moreembodiments.

FIGS. 10, 11, 12, and 13 illustrate various methods for synchronizingintegrated circuit chips, according to one or more embodiments.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. It is contemplated that elements disclosed in oneembodiment may be beneficially utilized on other embodiments withoutspecific recitation. The drawings referred to here should not beunderstood as being drawn to scale unless specifically noted. Also, thedrawings are often simplified and details or components omitted forclarity of presentation and explanation. The drawings and discussionserve to explain principles discussed below, where like designationsdenote like elements.

DETAILED DESCRIPTION

The following detailed description is merely exemplary in nature and isnot intended to limit the disclosure or the application and uses of thedisclosure. Furthermore, there is no intention to be bound by anyexpressed or implied theory presented in the preceding background,summary, or the following detailed description.

In one or more embodiments, an input device includes multiple displaydriver integrated circuit chips configured for display updating andperforming capacitive sensing. Each of the display driver integratedcircuit chips is configured to drive sensor electrodes and updatedisplay electrodes of a common display panel, and artifacts and/orerrors in the sensing data may occur if the display driver integratedcircuit chips are not synchronized with each other. In the followingdescription, various systems and methods for synchronizing displaydriver integrated circuit chips are described.

Turning now to the figures, FIG. 1 is a block diagram of an exemplaryinput device 100, in accordance with embodiments of the disclosure. Theinput device 100 may be configured to provide input to an electronicsystem (not shown). As used in this document, the term “electronicsystem” broadly refers to any system capable of electronicallyprocessing information. Some non-limiting examples of electronic systemsinclude personal computers of all sizes and shapes, such as desktopcomputers, laptop computers, netbook computers, tablets, web browsers,e-book readers, and personal digital assistants (PDAs). Additionalexample electronic systems include composite input devices, such asphysical keyboards that include input device 100 and separate joysticksor key switches. Further example electronic systems include peripheralssuch as data input devices, e.g., remote controllers and mice, and dataoutput devices, e.g., display screens and printers. Other examplesinclude remote terminals, kiosks, and video game machines, e.g., videogame consoles, portable gaming devices, and the like. Other examplesinclude communication devices, e.g., cellular phones such as smartphones, and media devices, e.g., recorders, editors, and players such astelevisions, set-top boxes, music players, digital photo frames, anddigital cameras. Additionally, the electronic system could be a host ora slave to the input device. The electronic system may also be referredto as electronic device.

The input device 100 can be implemented as a physical part of theelectronic system, or can be physically separate from the electronicsystem. As appropriate, the input device 100 may communicate with partsof the electronic system using any one or more of the following: buses,networks, and other wired or wireless interconnections. Examples includeI²C, SPI, PS/2, Universal Serial Bus (USB), Bluetooth, RF, and IRDA.

In FIG. 1, the input device 100 is shown as a proximity sensor deviceconfigured to sense input provided by one or more input objects 140 in asensing region 120. Example input objects 140 include fingers and styli,as shown in FIG. 1. An exemplary proximity sensor device may be atouchpad, a touch screen, a touch sensor device and the like.

Sensing region 120 encompasses any space above, around, in and/or nearthe input device 100 in which the input device 100 is able to detectuser input, e.g., user input provided by one or more input objects 140.The sizes, shapes, and locations of particular sensing regions may varywidely from embodiment to embodiment. In some embodiments, the sensingregion 120 extends from a surface of the input device 100 in one or moredirections into space until signal-to-noise ratios prevent sufficientlyaccurate object detection. The distance to which this sensing region 120extends in a particular direction, in various embodiments, may be on theorder of less than a millimeter, millimeters, centimeters, or more, andmay vary significantly with the type of sensing technology used and theaccuracy desired. Thus, some embodiment's sense input that comprises: nocontact with any surfaces of the input device 100; contact with an inputsurface, e.g. a touch surface, of the input device 100: contact with aninput surface of the input device 100 coupled with some amount ofapplied force or pressure; and/or a combination thereof. In variousembodiments, input surfaces may be provided by surfaces of casingswithin which the sensor electrodes (also referred to herein as sensingelectrodes) reside, by face sheets applied over the sensor electrodes orany casings, etc. In some embodiments, the sensing region 120 has arectangular shape when projected onto an input surface of the inputdevice 100.

The input device 100 may utilize any combination of sensor componentsand sensing technologies to detect user input in the sensing region 120.The input device 100 comprises one or more sensing elements fordetecting user input. As several non-limiting examples, the input device100 may use capacitive, elastive, resistive, inductive, magnetic,acoustic, ultrasonic, and/or optical techniques.

Some implementations are configured to provide images that span one,two, three, or higher dimensional spaces. Some implementations areconfigured to provide projections of input along particular axes orplanes.

In some resistive implementations of the input device 100, a flexibleand conductive first layer is separated by one or more spacer elementsfrom a conductive second layer. During operation, one or more voltagegradients are created across the layers. Pressing the flexible firstlayer may deflect it sufficiently to create electrical contact betweenthe layers, resulting in voltage outputs reflective of the point(s) ofcontact between the layers. These voltage outputs may be used todetermine positional information.

In some inductive implementations of the input device 100, one or moresensing elements pick up loop currents induced by a resonating coil orpair of coils. Some combination of the magnitude, phase, and frequencyof the currents may then be used to determine positional information.

In some capacitive implementations of the input device 100, voltage orcurrent is applied to create an electric field. Nearby input objectscause changes in the electric field, and produce detectable changes incapacitive coupling that may be detected as changes in voltage, current,or the like.

Some capacitive implementations utilize arrays or other regular orirregular patterns of capacitive sensing elements to create electricfields. In some capacitive implementations, separate sensing elementsmay be ohmically shorted together to form larger sensor electrodes. Somecapacitive implementations utilize resistive sheets, which may beuniformly resistive.

Some capacitive implementations utilize “self-capacitance” (also oftenreferred to as “absolute capacitance”) sensing methods based on changesin the capacitive coupling between sensor electrodes and an inputobject. In various embodiments, an input object near the sensorelectrodes alters the electric field near the sensor electrodes, thuschanging the measured capacitive coupling. In one implementation, anabsolute capacitance sensing method operates by modulating sensorelectrodes with respect to a reference voltage, e.g. system ground, andby detecting the capacitive coupling between the sensor electrodes andinput objects.

Some capacitive implementations utilize “mutual capacitance” (also oftenreferred to as “transcapacitance”) sensing methods based on changes inthe capacitive coupling between sensor electrodes. In variousembodiments, an input object near the sensor electrodes alters theelectric field between the sensor electrodes, thus changing the measuredcapacitive coupling. In one implementation, a transcapacitive sensingmethod operates by detecting the capacitive coupling between one or moretransmitter sensor electrodes (also referred to herein as “transmitterelectrodes” or “transmitters”) and one or more receiver sensorelectrodes (also referred to herein as “receiver electrodes” or“receivers”). Transmitter sensor electrodes may be modulated relative toa reference voltage, e.g., system ground, to transmit transmittersignals. Receiver sensor electrodes may be held substantially constantrelative to the reference voltage to facilitate receipt of resultingsignals. A resulting signal may comprise effect(s) corresponding to oneor more transmitter signals, and/or to one or more sources ofenvironmental interference, e.g. other electromagnetic signals. Sensorelectrodes may be dedicated transmitters or receivers, or may beconfigured to both transmit and receive.

In FIG. 1, a processing system 110 is shown as part of the input device100. The processing system 110 is configured to operate the hardware ofthe input device 100 to detect input in the sensing region 120. Theprocessing system 110 comprises parts of or all of one or moreintegrated circuits (ICs) and/or other circuitry components. Forexample, a processing system for a mutual capacitance sensor device maycomprise transmitter circuitry configured to transmit signals withtransmitter sensor electrodes, and/or receiver circuitry configured toreceive signals with receiver sensor electrodes. In some embodiments,the processing system 110 also comprises electronically-readableinstructions, such as firmware code, software code, and/or the like. Insome embodiments, components composing the processing system 110 arelocated together, such as near sensing element(s) of the input device100. In other embodiments, components of processing system 110 arephysically separate with one or more components close to sensingelement(s) of input device 100, and one or more components elsewhere.For example, the input device 100 may be a peripheral coupled to adesktop computer, and the processing system 110 may comprise softwareconfigured to run on a central processing unit of the desktop computerand one or more ICs (in another embodiment, with associated firmware)separate from the central processing unit. As another example, the inputdevice 100 may be physically integrated in a phone, and the processingsystem 110 may comprise circuits and firmware that are part of a mainprocessor of the phone. In some embodiments, the processing system 110is dedicated to implementing the input device 100. In other embodiments,the processing system 110 also performs other functions, such asoperating display screens, driving haptic actuators, etc.

The processing system 110 may be implemented as a set of modules thathandle different functions of the processing system 110. Each module maycomprise circuitry that is a part of the processing system 110,firmware, software, or a combination thereof. In various embodiments,different combinations of modules may be used. Example modules includehardware operation modules for operating hardware such as sensorelectrodes and display screens, data processing modules for processingdata such as sensor signals and positional information, and reportingmodules for reporting information. Further example modules includesensor operation modules configured to operate sensing element(s) todetect input, identification modules configured to identify gesturessuch as mode changing gestures, and mode changing modules for changingoperation modes.

In some embodiments, the processing system 110 responds to user input(or lack of user input) in the sensing region 120 directly by causingone or more actions. Example actions include changing operation modes,as well as GUI actions such as cursor movement, selection, menunavigation, and other functions. In some embodiments, the processingsystem 110 provides information about the input (or lack of input) tosome part of the electronic system, e.g., to a central processing systemof the electronic system that is separate from the processing system110, if such a separate central processing system exists. In someembodiments, some part of the electronic system processes informationreceived from the processing system 110 to act on user input, such as tofacilitate a full range of actions, including mode changing actions andGUI actions.

For example, in some embodiments, the processing system 110 operates thesensing element(s) of the input device 100 to produce electrical signalsindicative of input (or lack of input) in the sensing region 120. Theprocessing system 110 may perform any appropriate amount of processingon the electrical signals in producing the information provided to theelectronic system. For example, the processing system 110 may digitizeanalog electrical signals obtained from the sensor electrodes. Asanother example, the processing system 110 may perform filtering orother signal conditioning. As yet another example, the processing system110 may subtract or otherwise account for a baseline, such that theinformation reflects a difference between the electrical signals and thebaseline. As yet further examples, the processing system 110 maydetermine positional information, recognize inputs as commands,recognize handwriting, and the like.

“Positional information” as used herein broadly encompasses absoluteposition, relative position, velocity, acceleration, and other types ofspatial information. Exemplary “zero-dimensional” positional informationincludes near/far or contact/no contact information. Exemplary“one-dimensional” positional information includes positions along anaxis. Exemplary “two-dimensional” positional information includesmotions in a plane. Exemplary “three-dimensional” positional informationincludes instantaneous or average velocities in space. Further examplesinclude other representations of spatial information. Historical dataregarding one or more types of positional information may also bedetermined and/or stored, including, for example, historical data thattracks position, motion, or instantaneous velocity over time.

In some embodiments, the input device 100 is implemented with additionalinput components that are operated by the processing system 110 or bysome other processing system. These additional input components mayprovide redundant functionality for input in the sensing region 120, orsome other functionality. FIG. 1 shows buttons 130 near the sensingregion 120 that can be used to facilitate selection of items using theinput device 100. Other types of additional input components includesliders, balls, wheels, switches, and the like. Conversely, in someembodiments, the input device 100 may be implemented with no other inputcomponents.

In some embodiments, the input device 100 comprises a touch screeninterface, and the sensing region 120 overlaps at least part of adisplay screen. For example, the sensing region 120 may overlap at leasta portion of an active area of a display screen. The active area of thedisplay screen may correspond to a portion of the display screen whereimages are updated. In one or more embodiments, the input device 100 maycomprise substantially transparent sensor electrodes overlaying thedisplay screen and provide a touch screen interface for the associatedelectronic system. The display screen may be any type of dynamic displaycapable of displaying a visual interface to a user, and may include anytype of light emitting diode (LED), organic LED (OLED), cathode ray tube(CRT), liquid crystal display (LCD), plasma, electroluminescence (EL),or other display technology. The input device 100 and the display screenmay share physical elements. For example, some embodiments may utilizesome of the same electrical components for displaying and sensing. Asanother example, the display screen may be operated in part or in totalby the processing system 110. The display screen may also be referred toas a display panel.

It should be understood that while many embodiments of the disclosureare described in the context of a fully functioning apparatus, themechanisms of the present disclosure are capable of being distributed asa program product, e.g., software, in a variety of forms. For example,the mechanisms of the present disclosure may be implemented anddistributed as a software program on information bearing media that arereadable by electronic processors, e.g., non-transitorycomputer-readable and/or recordable/writable information bearing mediareadable by the processing system 110. Additionally, the embodiments ofthe present disclosure apply equally regardless of the particular typeof medium used to carry out the distribution. Examples ofnon-transitory, electronically readable media include various discs,memory sticks, memory cards, memory modules, and the like.Electronically readable media may be based on flash, optical, magnetic,holographic, or any other storage technology.

FIG. 2 shows a portion of an exemplary pattern of sensor electrodes 205configured to sense in the sensing region 120 associated with a pattern,according to some embodiments. For clarity of illustration anddescription, FIG. 2 presents the regions of the capacitive sensorelectrodes 205 in a pattern of simple rectangles; however, in otherembodiments, the sensor electrodes 205 may be disposed in other patternsand may have other shapes. For example, one or more of sensor electrodes205 may span the entirety of the sensing region 120 in a first direction(e.g., along the X axis) and another one or more of sensor electrodesmay span the entity of the sensing region in a second direction (alongthe Y axis) different than the first direction. Further, in variousembodiments, the sensor electrodes 205 may be disposed as overlapping ornon-overlapping rows and columns of sensor electrodes.

In one embodiment, the sensor electrodes 205 form areas of localizedcapacitance. The areas of localized capacitance may be formed between anindividual sensor electrode and ground in a first mode of operation andbetween groups of sensor electrodes used as transmitter and receiverelectrodes in a second mode of operation. The capacitive couplingchanges with the proximity and motion of input objects in the sensingregion 120, and thus may be used as an indicator of the presence of theinput object in the sensing region 120 of the input device.

The exemplary pattern comprises an array of sensor electrodes 205 _(X,Y)arranged in X columns and Y rows in a common plane, wherein X and Y arepositive integers, although one of X and Y may be zero. It iscontemplated that the pattern of sensing electrodes 205 may comprises aplurality of sensing pixels 205 having other configurations, such aspolar arrays, repeating patterns, non-repeating patterns, non-uniformarrays a single row or column, or other suitable arrangement. Further,as will be discussed in more detail below, the sensor electrodes 205 maybe any shape such as circular, rectangular, diamond, star, square,noncovex, convex, nonconcave concave, etc. As shown here, the sensorelectrodes 205 are coupled to the processing system 110 and utilized todetermine the presence of (or lack thereof) an input object in thesensing region 120.

In a first mode of operation, at least one sensor electrode may beutilized to detect the presence of an input object via absolute sensingtechniques. A sensor module 204 in processing system 110 is configuredto drive a sensor electrode using a trace 240 in each sensor electrode205 with a an absolute capacitive sensing signal and measure acapacitance between the sensor electrode and the input object based onthe absolute capacitive sensing signal, which is utilized by theprocessing system 110 or other processor to determine the position ofthe input object. The absolute capacitive sensing signal may be amodulated signal comprising a varying voltage. In one embodiment, theabsolute capacitive sensing signal includes a plurality of pulses (e.g.,a plurality of positive and negative voltage transitions). Further, apositive and negative voltage transition may be referred to as a burst,and the absolute capacitive sensing signal includes one or more bursts.

One or more of sensor electrodes 205 may be ohmically isolated fromanother one or more of sensor electrodes 205. Further, one or moreinsulators separate the sensor electrodes and prevent them fromelectrically shorting to each other.

In a second mode of operation, sensor electrodes 205 are utilized todetect the presence of an input object via transcapacitance sensingtechniques. That is, processing system 110 may drive at least one sensorelectrode 205 with a transmitter signal and receive resulting signalsusing one or more of the other sensor electrodes 205, where a resultingsignal comprising effects corresponding to the transmitter signal. Theresulting signal is utilized by the processing system 110 or otherprocessor to determine the position of the input object. The sensorelectrodes that are driven with the transmitter signal are modulated bythe transmitter signal relative to the sensor electrodes that receivethe resulting signals. In one embodiment, both the sensor electrodesthat are driven with the transmitter signal and the sensor electrodesthat receive the resulting signals are modulated. In one embodiment, thetransmitter signal includes a plurality of pulses (e.g., a plurality ofpositive and negative voltage transitions). Further, a positive andnegative voltage transition may be referred to as a burst, and thetransmitter signal includes one or more bursts.

The term “sensing signal” may refer to either an absolute capacitivesensing signal or a transmitter signal.

The input device 100 may be configured to operate in any one of themodes described above. The input device 100 may also be configured toswitch between the two modes described above.

In some embodiments, the sensor electrodes 205 are “scanned” todetermine these capacitive couplings. That is, in one embodiment, one ormore of the sensor electrodes are driven to transmit transmittersignals. Transmitters may be operated such that one transmitterelectrode transmits at one time, or multiple transmitter electrodestransmit at the same time. Where multiple transmitter electrodestransmit simultaneously, the multiple transmitter electrodes maytransmit the same transmitter signal and effectively produce aneffectively larger transmitter electrode. Alternatively, the multipletransmitter electrodes may transmit different transmitter signals. Forexample, multiple transmitter electrodes may transmit differenttransmitter signals according to one or more coding schemes that enabletheir combined effects on the resulting signals of receiver electrodesto be independently determined.

The sensor electrodes configured as receiver sensor electrodes may beoperated singly or multiply to acquire resulting signals. The resultingsignals may be used to determine measurements of the capacitivecouplings at the capacitive pixels 205.

In other embodiments, “scanning” sensor electrodes 205 to determinethese capacitive coupling includes driving with an absolute capacitivesensing signal and measuring the absolute capacitance of one or more ofthe sensor electrodes. In another embodiment, the sensor electrodes maybe operated such that the absolute capacitive sensing signal is drivenon a sensor electrode 205 at the same time. In such embodiments, anabsolute capacitive measurement may be obtained from each of the one ormore sensor electrodes 205 simultaneously. In one embodiment, the inputdevice 100 simultaneously drives a sensor electrode in a plurality ofsensor electrodes 205 and measures an absolute capacitive measurementfor each of the sensor electrodes 205 in the same sensing cycle. Invarious embodiments, processing system 110 may be configured toselectively drive and receive with a portion of sensor electrodes. Forexample, the sensor electrodes may be selected based on, but not limitedto, an application running on the host processor, a status of the inputdevice, an operating mode of the sensing device and a determinedlocation of an input device. The host processor may be a centralprocessing unit or any other processor of an electronic device.

A set of measurements from the sensor electrodes 205 form a capacitiveimage or capacitive frame representative of the capacitive couplings atthe sensor electrodes 205 as discussed above. Multiple capacitive imagesmay be acquired over multiple time periods, and differences between themused to derive information about input in the sensing region. Forexample, successive capacitive images acquired over successive periodsof time can be used to track the motion(s) of one or more input objectsentering, exiting, and within the sensing region.

In some embodiments, one or more of the sensor electrodes 205 includeone or more display electrodes used in updating the display of thedisplay screen. In one or more embodiment, the display electrodescomprise one or more segments of a common voltage electrode, alsoreferred to as a Vcom electrode, a source drive line (or sourceelectrode), gate line (or gate electrode), an anode electrode or cathodeelectrode, or any other display element. These display electrodes may bedisposed on an appropriate display screen substrate. For example, indisplay screens such as In Plane Switching (IPS) and Plane to LineSwitching (PLS) Organic Light Emitting Diode (OLED), the displayelectrodes may be disposed on a transparent substrate, e.g., a glasssubstrate, TFT glass, or any other transparent material). In otherembodiments, in display screens such as Patterned Vertical Alignment(PVA) and Multi-domain Vertical Alignment (MVA), the display electrodesmay be disposed on the bottom of a color filter glass. In one or moreembodiments, the display electrodes may be disposed over an emissivelayer of an OLED display. In such embodiments, an electrode that is usedas both a sensor electrode and a display electrode can also be referredto as a combination electrode, since it performs multiple functions. Inone embodiment, the display electrodes may be gate electrodes used toselect subpixels of a display line for updating, source electrodesconfigured to drive the data signals onto the subpixels for updatingand/or a Vcom electrode or electrodes. The source electrodes may becoupled to columns of subpixels and the gate electrodes may be coupledto rows of subpixels.

Continuing to refer to FIG. 2, in various embodiments, the processingsystem 110 coupled to the sensing electrodes may include one or moreintegrated circuit (IC) chips where each IC chip includes a sensormodule 204 and a display driver module 208. In one embodiment, thesensor module 204 comprises circuitry configured to drive a transmittersignal or an absolute capacitive sensing signal onto the sensingelectrodes and receive resulting signals with the sensing electrodesduring periods in which input sensing is desired. Further, theprocessing system may include multiple IC chips, where each IC chip mayinclude a sensor module 204 and a display driver module 208.

In one or more embodiments, the sensor module 204 comprises atransmitter module including circuitry configured to drive a transmittersignal onto the sensing electrodes during periods in which input sensingis desired. In one or more embodiments, the transmitter signal ismodulated and contains one or more bursts over a period of timeallocated for input sensing. The transmitter signal may have anamplitude, frequency and voltage which may be changed to obtain morerobust location information of the input object in the sensing region120. The absolute capacitive sensing signal may be the same or differentfrom the transmitter signal used in transcapacitance sensing. The sensormodule 204 may be selectively coupled to one or more of the sensorelectrodes 205. For example, the sensor module 204 may be coupled toselected portions of the sensor electrodes and operate in either anabsolute or transcapacitance sensing mode. In another example, thesensor module 204 may be coupled to different sensor electrodes whenoperating in the absolute sensing mode than when operating in thetranscapacitance sensing mode.

In various embodiments, the sensor module 204 comprises sensor circuitry(e.g., sensor circuitry 206 of FIG. 3) and the sensor module isconfigured to receive a resulting signal with the sensing electrodescomprising effects corresponding to the transmitter signal duringperiods in which input sensing is desired. In one or more embodiments,the sensor module 204 is configured to receive a resulting signal from asensor electrode that is driven with an absolute capacitive sensingsignal to determine changes in absolute capacitance between the sensorelectrode and an input object. In one or more embodiments, the sensormodule 204 determines a position of the input object in the sensingregion 120. In one or more embodiments, the sensor module 204 provides asignal including information indicative of the resulting signal toanother module or processor such as a determination module of theprocessing system 110 or a processor of the electronic device, e.g., ahost processor, for determining the position of the input object in thesensing region 120. In one or more embodiments, the sensor circuitry ofthe sensor module comprises receiver circuitry, where the receivercircuitry may include a plurality of analog front ends (AFEs).

In one or more embodiments, capacitive sensing or input sensing anddisplay updating may occur during at least partially overlappingperiods. Display updating may include updating the voltages on each ofthe display electrodes during a display frame. During each displayframe, each of display line of the display device may be updated. In oneembodiment, a display frame may be updated once every 16 ms or at adisplay frame rate of 60 Hz. In other embodiments, other display framerates may be utilized. For example, display frame rates of 48 Hz, 120Hz, and/or 240 Hz may be utilized. For example, as a combinationelectrode is driven for display updating, the combination electrode mayalso be driven for capacitive sensing. Overlapping capacitive sensingand display updating may include modulating the reference voltage(s) ofthe display device and/or modulating at least one display electrode fora display in a time period that at least partially overlaps with whenthe sensor electrodes are configured for capacitive sensing. In anotherembodiment, capacitive sensing and display updating may occur duringnon-overlapping periods, also referred to as non-display update periods.In various embodiments, the non-display update periods may occur betweendisplay line update periods for two display lines of a display frame andmay be at least as long in time as the display update period. In suchembodiment, the non-display update period may be referred to as a longhorizontal blanking period, long h-blanking period or a distributedblanking period. In other embodiments, the non-display update period maycomprise horizontal blanking periods and vertical blanking periods.Processing system 110 may be configured to drive sensor electrodes forcapacitive sensing during any one or more of or any combination of thedifferent non-display update times.

FIG. 3 illustrates a multiple IC chip solution for driving a displaypanel. In one or more embodiments, the display device 300 may be part ofan input device (e.g., input device 100) for a vehicle (e.g.,automobile). As illustrated, FIG. 3 includes a display device 300 havinga display panel with a substrate 320 and display electrodes 330. In theillustrated embodiment, three IC chips (e.g., the master IC chip 340,the right slave IC Chip 350, and the left slave IC chip 360) areutilized to drive the display panel and perform capacitive sensing. Inone embodiment, one or more of the IC chips may be disposed on a firstsubstrate and another one or more of the IC chips may be disposed on asecond substrate.

Each of the IC chips may include an instance of the sensor module 204and the display driver module 208. Further, each of the IC chips mayinclude a timing controller (Tcon) 209 configured to generate timingsignals for display updating and capacitive sensing and sensingcircuitry 206 configured to perform capacitive sensing with the sensorelectrodes 205. In one embodiment, the Tcon 209 is configured tocommunicate with capacitive sensing circuitry configured to synchronizedisplay updating and capacitive sensing.

In various embodiments, each of the IC chips 340, 350 and 360 includes aplurality of input/output pins. For example, as is illustrated in FIG.3, IC chips 340, 350, and 360 include input/output pins such assense_sync_i/o_l, sense_sync_i/o_r, tsvd_i/o_l, tsvd_i/o_r, tshd_i/o_l,tshd_i/o_r, Hcal_pulse_i/o_l, Hcal_pulse_i/o_r, general purposeinput/output (GPIO) pins. Input/output pins of an IC chip may becommunicatively coupled to associated input/output pins of another ICchip via one or more routing lines disposed on the substrate 320, or inone or more embodiments, between IC chips disposed on differentsubstrates. For example, sense_sync_i/o_l of the master IC chip 340 maybe coupled to sense_sync_i/o_r of the left slave IC chip 360, andsense_sync_i/o_r of the master IC chip 340 may be coupled tosense_sync_i/o_l of the right slave IC chip 350. Similarly, for example,tsvd_i/o_l of the master IC chip 340 may be coupled to tsvd_i/o_r of theleft slave IC chip 360, and tsvd_i/o_r of the master IC chip 340 may becoupled to tsvd_i/o_l of the right slave IC chip 350. Further,tshd_i/o_l of the master IC chip 340 may be coupled to tshd_i/o_r of theleft slave IC chip 360, and tshd_i/o_r of the master IC chip 340 may becoupled to tshd_i/o_l of the right slave IC chip 350. Hcal_pulse_i/o_lof the master IC chip 340 may be coupled to Hcal_pulse_i/o_r of the leftslave IC chip 360, and Hcal_pulse_i/o_r of the master IC chip 340 may becoupled to Hcal_pulse_i/o_l of the right slave IC chip 350.

In other embodiments, each of the IC chips may include otherinput/output pins. For example, each of the IC chips may includeinput/output pins that are used to drive the sensor electrodes 205 forcapacitive sensing and drive the display electrodes for displayupdating.

In one or more embodiment, an IC chip (e.g., the master IC chip 340, theright slave IC chip 350, and the left slave IC chip 360) that isconfigured for both capacitive sensing and display updating may bereferred to as a touch and display driver integration (TDDI) chip. Forexample, the IC chips may be configured to drive one or more sensorelectrodes 205 for at least one of transcapacitive sensing and absolutecapacitive sensing.

While the embodiment of FIG. 3 illustrates three IC chips, in otherembodiments, other numbers of IC chips may be implemented within theinput device 100. For example, in one embodiment, at least two IC chipsmay be utilized to drive the display panel and perform touch sensing.Each IC chip may include a separate and distinct IC from the other ICchips. Further, each of the IC chips may be configured to update adifferent portion of the display panel and operate a different portionof the sensor electrodes 205 (e.g., sensor electrodes 205 a, 205 b, and205 c) for capacitive sensing. In one or more embodiments, two or moreIC chips may drive at least one common sensor electrode 205 forcapacitive sensing. In one embodiment, each IC chip is coupled to andconfigured to update a different portion of the source electrodes orlines of the display panel. Further, an IC chip may be configured todrive a different portion of the Vcom electrodes for display updating.In embodiments where the Vcom electrodes are used for capacitive sensingand display updating, each IC chip is configured to operate a differentportion of the Vcom electrodes for capacitive sensing and displayupdating.

In one embodiment, each of the master IC chip 340, the right save ICchip 350, and the left slave IC chip 360) is independently coupled tosubstrate 320 of the display panel. Further, the master IC chip iscoupled to each slave IC chip by one or more traces disposed on thesubstrate 320. In one embodiment, the substrate 320 is a glass substrateand the IC chips are communicatively couple via one or more tracesdisposed on the glass substrate.

In embodiments employing two or more IC chips, one IC chip may beconfigured as a “master” (e.g., the master IC chip 340) and the other ICchips (e.g., the slave IC chips 350 and/or 360) may be configured as“slaves.” IC chips configured as a “master” may be configured to provideone or more synchronization signals to the IC chips configured as“slaves” to synchronize at least one of display updating and capacitivesensing functions between the IC chips. In embodiments employing threeIC chips, the master IC chip may be disposed between the two slave ICchips. In other embodiments, the master IC chip may be positioned suchthat each of the slave IC chips is on the same side of the master ICchip.

The master IC chip 340 may be configured to receive display data from ahost processor for updating the display panel. For example, the masterIC chip 340 may process the display data, and communicate the processeddisplay data to the slave IC chips 350 and 360. Further, the master ICchip 340 may be configured to communicate sensor data to a hostprocessor. For example, the master IC chip 340 may be configured toreceive sensor data from each of the slave IC chips 350 and 360, combinethe sensor data from the slave IC chips with the sensor data from themaster IC chip, and communicate the combined sensor data to the hostprocessor. In one embodiment, each of the IC chips may configured toprocesses the sensor data received at each respective IC chip before itis sent to the host processor. In other embodiments, raw sensor data(e.g., sensor data that is substantially unprocessed) is communicated tothe host processor. In other embodiments, the master IC chip 340 isconfigured to receive raw sensor data from each of the slave IC chips350 and 360, process the sensor data and then communicate the processedsensor data to the host processor. Processing the sensor data mayinclude at least one of baselining the sensor data, filtering the sensordata, and determining positional information of one or more inputobjects.

In one or more embodiments, the master IC chip 340 and the slave ICchips 350, 360 may be synchronized such that the digital circuits ofeach IC chip operate within at least about 50 ns with each other ICchip. In other embodiments, the IC chips may be synchronized with eachother such that the timing of the digital circuitry of each IC chipdiffers by more than 50 ns but doesn't introduce errors within thesensor data or display update. In one embodiment, the IC chips may besynchronized with each other such that the timing of the digitalcircuitry of each IC chip doesn't introduce display artifacts whenupdating the display panel and/or introduce errors into the sensor dataacquired from the sensor electrodes. Further, synchronizing the IC chipssynchronizes the timing of the sensing signals driven by each of the ICchips onto respective sensor electrodes 205.

In one embodiment, any timing mismatch between the sensing signals(e.g., sensing signals 342, 352, and 362) across the master IC chip 340and the slave IC chips 350 and 360 may result in imperfectly guardeddisplay panel capacitance, resulting in large amounts of charge to flowinto the AFEs of the receiver circuitry of each IC chip. In suchembodiments, one or more display electrodes of the display panel orsensor electrodes are at a different voltage than a sensor electrodeoperated for capacitive sensing. A capacitive coupling is formed betweenthe voltage mismatched electrodes, which may be referred to as abackground capacitance.

As the background capacitance is present in the sensor data acquiredfrom the sensor electrodes, the dynamic range of the receiver circuitryavailable to handle potential interference and changes in capacitance ofthe sensor electrodes is diminished. In one embodiment, the value of thebackground capacitance may be greater than the value of the capacitivecoupling between the sensor electrodes 205 and/or between a sensorelectrode 205 and an input object. Thus it is difficult to detect and/ormeasure the capacitive coupling between the sensor electrodes and/orbetween a sensor electrode and an input object. Further, the backgroundcapacitance may cause the AFE of the receiver circuitry to saturate orclip, making it impossible to detect and/or measure the capacitivecoupling between the sensor electrodes and/or between a sensor electrodeand an input object.

In one or more embodiments, the master IC chip 340 is configured toperform one or more of frame synchronization, sensing burstsynchronization, sensing cycle synchronization, and high speedoscillator clock synchronization with each of the slave IC chips 350,360.

Each IC chip 340, 350, 360 may be configured to operate a differentportion of the sensor electrodes 205 for capacitive sensing at acapacitive frame rate at one of 60 Hz or 120 Hz. In other embodiments,other capacitive frame rates may be utilized. In one embodiment, each ICchip 340, 350, 360 is coupled to each non-overlapping portion of thesensor electrodes 205 such that a sensor electrode is only coupled toone of IC chips 340, 350, and 360. For example, the slave IC chip 360 iscommunicatively coupled to sensor electrodes 205 a, the master slave ICchip 340 is communicatively coupled to sensor electrodes 205 b, and theslave IC chip 350 is communicatively coupled to sensor electrodes 205 c.The IC chips may be coupled to the same number of sensor electrodes, or,in one or more embodiments, at least IC chip is coupled to a differentnumber (e.g., more or less) of sensor electrodes than another IC chip.The IC chips may be coupled to respective sensor electrodes via one ormore routings disposed on the substrate 320. In other embodiments, theremay be some overlapping portions of the sensor electrodes 205 coupled toone or more of the IC chips 340, 350, 360.

Each IC chip may be configured to operate each respective sensorelectrode once (or twice) per each capacitive frame. In one embodiment,operating the sensor electrodes for capacitive sensing includes drivethe respective sensor electrodes with a respective one of sensingsignals 342, 352, 362. The capacitive frame rate corresponds to a periodof time during which sensor data is received from sensor electrodescoupled with each respective IC chip. In one embodiment, the rate atwhich the capacitive images are acquired is the capacitive frame rate(or sensing rate). For example, a capacitive image may be acquired onceevery 16 ms, generating a capacitive frame rate of 60 Hz. In otherembodiments, the capacitive frame rate may be about 120 Hz, 240 Hz, orgreater. Further, in one or more embodiments, the capacitive frame ratemay be less than 60 Hz.

The master IC chip 340 may be configured to perform framesynchronization with each of the slave IC chips 350, 360 such that eachIC chip begins a new capacitive frame at substantially the same time. Inone embodiment, frame synchronization may occur at the startup of the ICchips, after a reset of one or more IC chips, and/or after a number ofcapacitive frames has occurred.

The Tcon 209 of each IC chip 340, 350, 360 may generate timing controlsignals that may be employed by the IC chip to perform display updatingand capacitive sensing. In one embodiment, the timing signal which isused to indicate the start one or more of a capacitive sensing frame anda display frame is a timing signal for the vertical direction (i.e.,vertical timing signal) or tsvd signal. Further, a timing signalconfigured to indicate the start of a display line of the display frameis a timing signal for the horizontal direction (i.e., horizontal timingsignal) or tshd signal. Both of the tsvd and tshd signals may begenerated by the Tcon 209 of the master IC chip 340 and communicated toeach of the slave IC chips 350, 360.

FIG. 4 illustrates an example embodiment of trigger look up table (LUT)logic 410. In one embodiment, each of the IC chips 340, 350, 360includes a trigger LUT logic 410. The tsvd signal generated by the Tcon209 of the master IC chip 340 may be routed to the trigger LUT logic ofeach of the master IC chip 340 and the slave IC chip 350, 360. In oneembodiment, the tsvd signal may be communicated from tsvd_i/o_l andtsvd_i/o_r of the master IC chip 340 to tsvd_i/o_r of the left slave ICchip 360 and tsvd_i/o_l of the right slave IC chip 350. Further, Tcon209 of the master IC chip 340 may be configured to communicate a tshdsignal to each of the slave IC chips 350, 360. For example, the tshdsignal may be communicated from tshd_i/o_l and tshd_i/o_r of the masterIC chip 340 to pin tshd_i/o_r of the right slave IC chip 360 andtshd_i/o_l the left slave IC chip 350.

Tcon 209 of the master IC chip 340 communicates both the tsvd and tshdsignals to the trigger LUT logic 410 of the master IC chip 340, as wellas to the trigger LUT logic 410 of each of the slave IC chips 350, 360.The trigger LUT logic 410 of each slave IC chip 350, 360 is configuredto generate a local sense_trig_event pulse 420 from the tsvd and tshdsignals provided by the master IC chip 340. Further, each IC chip 340,350, and 360 may initiate a burst sensing state machine that enables theacquisition of sensor data in response to the respective localsense_trig_event pulse 420. The burst sensing state machine of each ICchip initiates the steps utilized to acquire sensor data correspondingto the bursts of the sensing signal.

The INT_TCON_TRIG registers 432, 434 allows an IC chip to use a TCON ofthe IC chip to generate respective tshd and tsvd signals. TheSLAVE_SELECT registers 436, 438 specify whether a chip is in a single ICconfiguration, configured as a master IC chip, configured as a leftslave IC chip, or configured as a right slave IC chip. Further, thesense_trig_event signal 420 may be utilized by each respective IC chipto initiate a sensing burst. Each sensing burst corresponds to at leastone positive and negative voltage transition. Each sensing signalincludes a plurality of bursts. In one embodiment, the SLAVE_SELECTregisters 436, 438 and the INT_TCON_TRIG registers 432, 434 arecommunicatively coupled with multiplexers 462 and 464 and may controlthe single coupled by the multiplexers 462 and 464 into the trigger LUT410. For example, the SLAVE_SELECT registers 436 and the INT_TCON_TRIGregisters 432 are utilized to select one of the tshd_in_l_dest,tshd_in_r_dest, Tshd_Tcon signals coupled by multiplexer 462 intotrigger LUT 410. Further, the SLAVE_SELECT registers 438 and theINT_TCON_TRIG registers 434 are utilized to select one of thetsvd_in_l_dest, tsvd_in_r_dest, Tsvd_Tcon signals coupled by multiplexer464 into trigger LUT 410.

At the start of a new capacitive frame, the FW_SENSE_TRIG register 450is programmed to generate a sense_trig_event signal 420 when the tsvdsignal is received. Further, as the tsvd signal is generated atsubstantially the same time for all the IC chips, the beginning of a newcapacitive frame will start at the same time for all the IC chips.

FIG. 5A illustrates diagrams that show the origination of the signalsused in the above figure above. Element 510 identifies input/output pinstsvd_in_l and tshd_in_l on the left side of the slave IC chip 360. Thesepins may receive the tsvd and tshd signals from the master IC chip 340.The tsvd_in_l pin and the tsh_in_l pin may be communicatively coupled totsvd_in_l_dest and tshd_in_l_dest inputs of multiplexers of the slave ICchip 360. Similarly, element 520 identifies input/output pins tsvd_in_rand tshd_in_r on the right side of the slave IC chip 350. These mayreceive the tsvd and tshd signals from the master IC chip 340. Thetsvd_in_l and the tsh_in_l may be communicatively coupled totsvd_in_r_dest and tshd_in_r_dest of the multiplexers of the slave ICchip 360. Further, Tcon 209 of the master IC chip 340 is configured tooutput signals tshd and tsvd to pins tshd_Tcon and tsvd_Tcon of themultiplexers coupled to the trigger LUT 410 of the master IC chip 340.

In one or more embodiments, the master IC chip 340 may be configured toperform burst synchronization with the slave IC chips 350 and 360. Burstsynchronization may occur once a burst, after a plurality of bursts,and/or once one or more capacitive frames. Each capacitive frame mayinclude multiple bursts. In one embodiment, the Tcon (e.g., Tcon 209) ofthe master IC chip 340 sends the tshd signal of the master IC chip tothe trigger LUT logic (e.g., trigger LUT logic 410) of the master ICchip 340. Further, after a first sensing burst of a capacitive frame,each IC chip employs a FW_SENSE_TRIG signal that is programmed togenerate a sense_trig_event signal based on a respective tshd signal. Asthe tshd signal arrives at substantially the same time for all three ICchips, each IC chip generates a sense_trig_event signal at roughly thesame time, which maintains burst synchronization.

FIG. 5B is a block diagram of system 500 configured to generate asense_trig_event signal 420 according to one or more embodiments. Asdescribed with regard to FIG. 4, in the embodiment of FIG. 5B, thesense_trig_event signal 420 may be initiated by the fw_sense_trig signal566. In one embodiment, synchronizers 550 and 552 may be utilized tosynchronize the tshd and tsvd signals with the corresponding signals ofthe master IC chip 340. As is illustrated in FIG. 5B, the tshd signal isinput into delay unit 540, and the tsvd signal is input into delay unit542. In one or more embodiments, both the tshd signal and the delayedtshd signal, and both the tsvd and the delayed tsvd signals are providedto LUT 544. Register sense_trig_LUT 548 may be utilized to controlgeneration of the sense_trig signal 546 by LUT 544. Sense_trig signal546 is utilized by pulse generator 560 to generate an output pulse 562.The pulse generator 560 outputs the pulse 562 for each detected risingedge of the sense_trig 546 signal. The output 562 of the pulse generator560 may be combined with a delayed fw_sense_trig_dlyd signal 564 togenerate the sense_trig_event pulse 420. The fw_sense_trig signal 566 isdelayed by delay unit 568 to generate the fw_sense_trig_dlyd signal 564.In one embodiment, delay units 540, 542 and 568 are programmable delaysthat ensure that each IC chip 340, 350, 360 generates thesense_trig_even pulse 420 at substantially the same time. Theprogrammable delays may be different for each of the IC chips. Further,in one or more embodiments, the programmable delays may be determined asdescribed in the following.

The sensing signals (e.g., Vguard signal) of the IC chips (e.g., themaster IC chip 340, the slave IC chips 350, 360) may be generated usinga waveform generator (e.g., a Direct Digital Synthesize (DDS) device orsimilar device). The sensing signal waveform may be periodic voltagewaveform that is generated by the waveform generator. In one embodiment,the waveform generator generates the sensing signal one half period at atime. In one embodiment, the waveform generator is reset at thebeginning of each sensing burst. Further, in one or more embodiments,the burst sensing state machine for each IC chip is also reset andinitiated at the beginning of each sensing burst. In one embodiment, thesensing signal may be driven onto one or more sensor electrodes toperform capacitive sensing and onto one or more display electrodes(e.g., gate electrodes, source electrodes, or the like) as a guardsignal to guard the display electrodes.

The master IC chip 340 may be configured to perform sense cyclesynchronization with the slave IC chips 350, 360. In one embodiment,synchronizing the sense cycle ensures that the waveform generator ofeach IC chip initiates every half period at substantially the same time.In one embodiment, the delay between the start of each half period is nogreater than about 50 ns between the three chips. In other embodiments,the delay between the start of each half period is less than a period oftime that may lead to display artifacts and errors within the sensordata.

FIGS. 6A and 6B each illustrate an example sense synchronization signalloopback path of the master IC chip according to one or moreembodiments. Each loopback path corresponds to a communicative couplingbetween a slave IC chip and a master IC chip. FIG. 6A illustrates theexample path 610 of the master IC chip for a left slave IC chip, andFIG. 6B illustrates the example path 620 of the master IC chip for aright slave IC chip. Further, in the embodiments illustrated in FIGS. 6Aand 6B, the master IC chip sends the sense_sync_out signal out of thewaveform generator 612 of the master IC chip. The label Start indicateswhere the path starts with the sense_sync_out signal 668 provided by thewaveform generator 612. The sense_sync_out signal 668 then flows alongthe indicated path 610 where it is routed out of the master IC chip.

In the embodiment of FIG. 6A, the sense_sync_out signal 668 flowsthrough a pulse_extension block 669, through a delay block (orsense_sync_out_l_DLY block) 617, and out through a sense_sync_out_l pin619 of the master IC chip 340 and then back into the master IC chip 340via a sense_sync_in_l pin 621. The sense_sync_out_l_DLY block 617 may bea programmable delay. Further, the signal through the sense_sync_in_lpin 621, that is the sense_sync_in_l_dest signal 622, flows throughmultiplexer 613, and then into the waveform generator 612 at the labelEnd via circuitry 614. The circuitry 614 generates a sense_sync_insignal 665 from the sense_sync_in_l_dest signal 622. The circuitry 614may include a delay block (or SENSE_SYNC_IN_LP_DLY block) 670 andmultiplexer 664.

In the embodiment of FIG. 6B, the sense_sync_out signal 668 flows alongpath 620 through a pulse_extension block 669, through a delay block (orsense_sync_out_r_DLY block) 671, and out through a sense_sync_out_r pin623 of the master IC chip and then back into the master IC chip via asense_sync_in_r pin 624. The sense_sync_out_r_DLY block 671 may be aprogrammable delay. Further, the signal through the sense_sync_in_r pin624, that is the sense_sync_in_r_dest signal 625, flows throughmultiplexer 613, and then into the waveform generator 612 at the labelEnd via circuitry 614.

In one or more embodiments, the master IC chip is configured tosimultaneously transmit sense_sync_out signals for slave IC chips (e.g.,right and left slave IC chips) that are coupled to the master IC chip,and a loopback path may be present for each of the slave IC chips.

FIG. 6C illustrates an example loopback path circuitry 660 for themaster IC chip according to one or more embodiments. This may be used inconjunction with the embodiments of FIG. 6A and FIG. 6B. As isillustrated, a sense_sync_short_lb signal 667 may be generated from thesense_sync_out signal 668. The sense_sync_short_lb signal 667 may beutilized as a trigger by the master IC chip 340 to generate thesense_sync_out signal 668 and synchronize the master IC chip 340 withthe slave IC chip 350, 360. For example, in one embodiment, as thesense_sync_short_lb signal 667 flows into the multiplexer 666 withoutbeing transmitted over input/output pins 619, 621, 623, and 624, thesense_sync_short_lb signal 667 may mitigate or avoid timing jitters asthe timing generated by the sense_sync_short_lb signal is not affectedby external interferences. This improves the synchronization between themaster IC chip 340, and the slave IC chips 350, 360.

Referring back to FIGS. 6A, 6B, and 6C, in one or more embodiments, themaster IC chip is configured to control which side of the master IC chip340, for example left or right, the signal is routed back to, via aselector such as SENSE_SYNC_IN_LR_SEL register 615 (FIGS. 6A and 6B) andSENSE_SYNC_IN_SEL register 616 (FIG. 6C) coupled to the multiplexer 613(FIGS. 6a and 6b ), 666 (FIG. 6c ). Further, the signal may be delayedby the SENSE_SYNC_IN_LP_DLY block 670. The SENSE_SYNC_IN_LP_DLY block670 may be a programmable delay. The signal then travels through themultiplexer 664 and is received by a sense_sync_in input port of themaster IC chip. The multiplexer 664 may be controlled via SLAVE_SELECTregister 618. In one embodiment, when the master IC chip 340 receivesthe sense_sync_out signal, a new half period of the sensing signal(e.g., sensing signal 342) is initiated.

FIGS. 7A and 7B illustrate embodiments where the master IC chipcommunicates the sense_sync_out signal 668 to slave IC chips for sensecycle synchronization. For example, in the embodiment of FIG. 7A, themaster IC chip 340 is communicatively coupled with the slave IC chip 350located to the right of the master IC chip 340. Further, in theembodiment of FIG. 7B, the master IC chip 340 is communicatively coupledwith the slave IC chip 360 located to the left of the master IC chip340. In one embodiment, the master IC chip 340 communicates thesense_sync_out signal 668 out of the same side of the master IC 340 chipalong where the slave IC chip is positioned. For example, the slave ICchip 350 is positioned along the right side of the master IC chip 340,and the sense_sync_out signal 668 is output from a pin along the rightside of the master IC chip 340. In other embodiments, the sense_sync_outsignal 668 may be output from a pin from a side of the master IC chip340 that is different than the side of the master IC chip 340 that theslave IC chip is positioned.

In one embodiment, the sense_sync_out signal 668 is delayed by aprogrammable delay before it is transmitted from the master IC chip 340to the slave IC chip 350, 360. The sense_sync_out signal 668 may then betransmitted out of a pin of the master IC chip 340 to a sense_sync_i/opin of the slave IC chip 350, 360. In one embodiment, a trace alongwhich the sense_sync_out signal 668 travels is disposed on a glasssubstrate of a display panel. The display panel may be part of an inputdevice (e.g., input device 100). In one embodiment, after thesense_sync_out signal 668 is received via the sense_sync_i/o pin of theslave IC chip, the sense_sync_out signal 668 is routed via a multiplexerto a waveform generator of the corresponding slave IC chip.

In one or more embodiments, when performing sense cycle synchronizationwith the slave IC chips 350, 360, the master IC chip 340 is configuredto utilize the programmable delays, e.g., sense_sync_out_r_dly 712 andsense_sync_out_l_dly 722, to synchronize the sense cycle of the masterIC chip 340 with the sense cycles of the slave IC chips 350, 360. Bytuning each of the programmable delays within the master IC chip 340,the sense cycle synchronization between the master IC chip 340 and eachslave IC chip 350, 360 may occur. In one embodiment, the amount of theprogrammable delays may be determined by performing one or more of thedelay calibration techniques describe herein. For example, theprogrammable delays may be calibrated such that the sense_sync_outsignal 668 generated by the master IC chip 340 arrives at the waveformgenerators 612, 612 a, 612 b of the IC chips 340, 350, 360 within about50 ns of each other. In other embodiments, the programmable delays maybe calibrated such that the sense_sync_out signal 668 is received by thewaveform generators 612, 612 a, 612 b of the IC chips 340, 350, 360within a period of time relative to each other that at least minimizeserrors and/or differences in the sensor data acquired by each of the ICchips.

In other embodiments, to perform delay calibration, the master IC chiptransmits a timing pulse along a loopback path within the master IC chipand along a round trip path to and back from the slave IC chip. Themaster IC chip may time the signal propagation of the timing pulse alongthese paths. For example, the master IC chip times the signalpropagation of the timing pulse that was transmitted via the loopbackpath of the master IC chip and the signal propagation of the timingpulse that was transmitted via the path from the master IC chip to theslave IC chip and then back to the master IC chip. The timing pulse maybe the sense_sync_out signal 668.

FIG. 8A is a diagram of the signal paths for performing delaycalibration in an embodiment having two slave IC chips 350, 360 and onemaster IC chip 340, according to one or more embodiments. In anembodiment, having a single slave IC chip and a master IC chip, one ormore of the signals paths may be omitted. For example, in an embodimentwhere the right slave IC chip is omitted, the corresponding signal pathsare also omitted. Further, in an embodiment where the left slave IC chipis omitted, the corresponding signal paths are also omitted.

In one embodiment, the master IC chip 340 initiates a delay calibrationclock and sends the sense_sync_out signal to the slave IC chips 350, 360via signal paths 812 and 813 and also locally onto both sides of themaster IC chip 340 that are coupled to the slave IC chips 350, 360 viasignal paths 810 and 811. The sense_sync_out signal propagates alongeach of paths 810-813 illustrated in FIG. 8A. For example, thesense_sync_out signal may be communicated from the master IC chip 340 toeach of the slave IC chips 350, 360 and then back onto the master ICchip 340. Further, the sense_sync_out signal may be transmitted locallyon the master IC chip 340 via the lookback path.

With reference to the loopback paths 810 and 811 of the master IC chip340, the sense_sync_out signal may be sent out at least one of the rightside (SSO_R) pad and the left side (SSO_L) pad. The sense_sync_outsignal may be looped back, on the pad, to the waveform generator of themaster IC chip 340 via the signal path 810, 811. In one embodiment, themaster IC chip 340 may measure only one of the loopback paths at a timeand determine the delay along which path, the left path or the rightpath, is measured. In the embodiment, for example, the value of theSENSE_SYNC_IN_LR_SEL register 615 of the master IC chip 340 may beutilized to make the determination. In other embodiments, each of thepaths may be simultaneously measured.

In one embodiment, the sense_sync_out signal is communicated to theright slave IC chip 350 via the SSO_R pad of the master IC chip. Thesense_sync_out signal travels across the substrate that each of the ICchips is mounted to, e.g., substrate 320, from the master IC chip 340 tothe SSI_L pad of the right slave IC chip 350. The right slave IC chip350 receives the sense_sync_out signal and routes the sense_sync_outsignal back out through the TSHDO_L pad, over the substrate to theTSHDI_R pad of the master IC chip 340. The master IC chip 340 receivesthis sense_sync_out signal, stops the timer, and records thecorresponding round trip propagation time.

In one embodiment, with reference to FIG. 7A, the timing signal, e.g.sense_sync_out signal 668, is transmitted from the waveform generator612 of the master IC chip 340, out of sense_sync_out_r pin 716 of themaster IC chip 340 to the sense_syc_in_l pin 720 of the slave IC chip350 and then to the waveform generator 612 a of the slave IC chip 350. Acounter is started when the timing signal is transmitted by the waveformgenerator 612. The timing signal is then transmitted out of the waveformgenerator 612 a through the sense_sync_out_l pin 740 of the slave ICchip 350 to the sense_sync_in_r pin 742 of the master IC chip 340 andthen into the waveform generator 612. The waveform generator 612 stopsthe counter when the signal timing signal is received. The value of thecounter corresponds to the amount of delay that between the master ICchip 340 and the slave IC chip 350.

In another embodiment, the sense_sync_out signal is communicated to theleft slave IC chip 360 via the SSO_L pad of the master IC chip 340. Thesense_sync_out signal travels across the substrate that each of the ICchips is mounted, e.g. substrate 320, from the master IC chip 340 to theSSI_L pad of the left slave IC chip 360. The left slave IC chip 360receives the sense_sync_out signal and routes the sense_sync_out signalback out through the TSHDO_R pad, over the substrate to the TSHDI_L padof the master IC chip 340. The master IC chip 340 receives thissense_sync_out, stops the timer, and records the corresponding roundtrip propagation time.

In one embodiment, with reference to FIG. 7B, the timing signal, e.g.sense_sync_out signal 668, is transmitted from the waveform generator612 of the master IC chip 340, out of sense_sync_out_l pin 718 of themaster IC chip 340 to the sense_syc_in_l pin 756 of the slave IC chip360 and then to the waveform generator 612 b of the slave IC chip 360. Acounter is started when the timing signal is transmitted by the waveformgenerator 612. The timing signal is then transmitted out of the waveformgenerator 612 b through the sense_sync_out_r pin 752 of the slave ICchip 360 to the sense_sync_in_l pin 754 of the master IC chip 340 andthen into the waveform generator 612. The waveform generator 612 stopsthe counter when the signal timing signal is received. The value of thecounter corresponds to the amount of delay that between the master ICchip 340 and the slave IC chip 360.

In one embodiment, the signal propagation measurement on master IC chiploopback path on the right side, e.g., path 811, may be referred to asM2M_R and on the left side, e.g., path 810 may be referred to as M2M_L.Further, the round trip signal propagation measurement from the masterIC chip 340 to the slave IC chip 350, e.g., path 812, may be referred toas M_RS_M. The round trip signal propagation measurement from the masterIC chip 340 to the slave IC chip 360, e.g., path 813 may be referred toas M_LS_M. Further, in one or more embodiments, paths 812 and 813 may besubstantially symmetric with each other.

In one embodiment, the signal propagation measurement M2M_R and/or theleft side is M2M_L are less than the signal propagation measurementsM_RS_M and M_LS_M. For example, the signal propagation measurement M2M_Rand/or the left side is M2M_L may be about 10 ns to about 30 ns, and thesignal propagation measurements M_RS_M and M_LS_M may be about 80 ns to100 ns.

In one embodiment, the programmable delay from the master IC chip 340 tothe right slave IC chip 350 may be determined by:

R _(DLY)=0.  Equation 1

In one embodiment, the programmable delay from the master IC chip 340 tothe left slave IC chip 360 may be determined by:

L _(DLY)=0.5*(M_RS_M−M_LS_M).  Equation 2

In one embodiment, the programmable delay on the loopback path of themaster IC chip 350 may be determined by:

LP _(DLY)=0.5*(M_RS_M+T _(sync))−M2M_R.  Equation 3

The left delay (L_(DLY)) may correspond to the difference in thepropagation times for the routing of the right slave IC chip 350 and theleft slave IC chip 360. Thus, the master IC chip 340 may be configuredto generate a delay that corresponds to the delay in routing between themaster IC chip 340 and the slave IC chips 350, 360. In one or moreembodiments, the propagation times of the different sides of the masterIC chip 340 may be used to further generate the programmable delay.

In one or more embodiments, the master-to-master loopback path (M2M_T)delay is about 2 touch-analog-control (TAC) clocks of delay. The TACclock may be used by the sensor module 204 and sensor circuitry 206 tocontrol acquisition of the sensor data from the sensor electrodes 205.Further, in various embodiments, M2M_T+LP_(DLY) is equal toM2LS+L_(DLY). Further, M2M_T may be a fixed delay of about 2, andL_(DLY) may about 0, 0.5*MLSM=M2LS or TchipL+TglassL+TchipR+Tsync+2.Thus, L_(DLY) may be equal to TchipL+TglassL+TchipR+Tsync. TglassL andTglassR corresponding to the routing delays between IC chips.

FIG. 8B illustrates the various signal paths between the master IC chip340 and each slave IC chip (e.g., left slave IC chip 360 and right slaveIC chip 350), according to one or more embodiments. For example, masterIC chip 340 transmits tshd, tsvd, sense_sync_out and HSO calibrationpulse out (hpo) signals to the slave IC chips 350, 360 via correspondinginput/output pins on the master IC chip 340 and the slave IC chips 350,360. In one embodiment, sense_sync_out signals are provided via signalpaths 824, 826, 836 and 838. Tshd signals may be provided via signalpaths 820, 822. Tsvd signals may be provided via signal paths 828, 830.The hpo signals may be provided via signal paths 832 and 834.

While four sets of input/output pin are used one either side of themaster IC chip 340 to communicate with each of the slave IC chips 350,360, in other embodiments, all of the input/output pins may be disposedalong a common side of the master IC chip 340. Further, instead of onegrouping of input/output pins being disposed along a side of the masterIC chip 340, one or more sides of the master IC chip 340 may includemultiple groupings of input/output pins. In such an embodiment, eachgrouping of pins corresponds to a different slave IC chip that may becoupled to the master IC chip 340.

In one or more embodiments, the master IC chip 340 may be configured tosynchronize the high-speed-oscillator (HSO) circuits of the slave ICchips 350, 360. The HSO circuits may generate a HSO clock signal that isutilized by the digital circuits of the respective IC chips. In oneembodiment, the TAC clock signal may be generated based on the HSOclock. Synchronizing the HSO clocks of the IC chips synchronizescapacitive sensing across all of the IC chips (e.g., 340, 350 and 360).In one embodiment, the HSO clocks may be calibrated to the substantiallythe same frequency. Each HSO clock may be calibrated to a frequencywithin about 0.2% tolerance with respect to one another. In otherembodiments, each HSO clock is calibrated to a frequency within atolerance other than 0.2% of each other such that errors are notintroduced in the sensing data acquired from the sensor electrodes 205.

In one embodiment, to synchronize the HSO clocks, the master IC chip 340transmits a periodic square wave signal 910 of programmable frequency toeach of the slave IC chips 350, 360, for example via the Hcal_pulse_i/opin (FIG. 3). The slave IC chips 350, 360 may use the square wave signal910 as an accurate time base for the clock of the master IC chip 340. Inone embodiment, a measurement period begins when each of the slave ICchip 350, 360 receives the first rising edge of the periodic square wave910. The measurement period may correspond to a number of clock pulsesof the clock of n each of the slave IC chips 350, 360 that occur beforea falling edge is detected after the first rising edge. In oneembodiment, each of the slave IC chips 350, 360 includes a register thatis used to count the number of clock pulses. In one embodiment, thenumber of clock pulses is about 8. In other embodiments, other numbersof clock pulses may be utilized.

FIG. 9 illustrates an example periodic square wave 910. The half periodof the square wave reference may be controlled by a HCAL_PULSE_DURregister of the master IC chip 340. In one embodiment, theHCAL_PULSE_DUR register is a 10 bit register. In other embodiments,registers having other sizes may be utilized. Equation 4 may be used todetermine the frequency of the square wave pulse.

$\begin{matrix}{f_{hcal} = {\frac{HSO\_ Clk}{2\left( {{HALF\_ PULSE}{\_ DUR}} \right)}.}} & {{Equation}\mspace{14mu} 4}\end{matrix}$

In one embodiment, on the rising edge of the square wave, each slave ICchip 350, 360 begins counting the number of rising edges of the HSOclock of each respective slave IC chip. If the slave IC chip HSO clockis perfectly aligned with that of the master IC chip, the slave IC chipwill measure 2*HALF_PULSE_DUR rising edges of its own HSO during oneperiod of the square wave reference. The slave IC chip may be configuredto count the number of its HSO rising edges over multiple periods of thesquare wave. The number of periods used to carry out this measurement iscontrolled by HSO_CALIB_TIME. The total number of rising edges of theHSO clock of the slave IC chip 350, 360 that occur during themeasurement window is stored in a register called HSO_CALIB_CNT of thecorresponding slave IC chip. The value of HSO_CALIB_CNT is governed byEquation 5:

$\begin{matrix}{{{HSO\_ CALIB}{\_ CNT}} = {2*{HSO\_ CALIB}{\_ TIME}*{HCAL\_ PULSE}{\_ DUR}*{\left( \frac{T_{masterHSO}}{T_{slaveHSO}} \right).}}} & {{Equation}\mspace{14mu} 5}\end{matrix}$

Each slave IC chip 350, 360 may measure HSO_CALIB_CNT during HSOcalibration, and after dividing by the known terms, the slave IC chip isleft with a measurement of

$\left( \frac{T_{masterHSO}}{T_{slaveHSO}} \right).$

Thus, each of the slave IC chips determines the fractional error betweenthe HSO clock and each respective slave IC chip and the HSO of themaster IC chip. As such, each of the slave IC chips is able to correctfor the HSO error by adjusting a register controlling the HSO clock ofthe slave IC chip. For example, each slave IC chip may adjust afrequency modulation (FMOD) register to adjust the HSO clock. In oneembodiment, the FMOD register is configured to shift the frequency ofthe HSO clock. In one or more embodiments, the FMOD register isconfigured to apply shifts of one or more Hz, and/or KHz to thefrequency of the HSO clock.

In one embodiment, when HSO_CALIB_CNT is 0, an indication that the slaveIC chip didn't receive enough pulses from the master IC chip 340 toaccurately perform HSO calibration may be generated. In one embodiment,HSO calibration is performed during power on of the IC chips, after areset of the IC chips, after a power down of the IC chips, and/or aftera number of sensing bursts have been completed. Further, HSO calibrationmay occur after a period of time to account for drift in the HSO clockof the either the master or slave IC chips. Further, tracking may beused to detect whether or not the slave or master clocks have drifted,and to initiate HSO calibration.

FIG. 10 illustrates method 1000 for synchronizing a master IC chip(e.g., master IC chip 340) with a slave IC chip (e.g., slave IC chip350, 360). At step 1010, a vertical timing signal (or tsvd) and ahorizontal timing signal (or tshd) are generated. In one embodiment, themaster IC chip 340 receives display data from a host processor,processes the display data and generates the vertical timing signal andthe horizontal timing signal. The vertical timing signal may correspondto the start of a display frame and the horizontal timing signal maycorrespond to the start of a display line. Further, the vertical timingsignal and the horizontal timing signal may include one or more pulses.In one or more embodiments, the vertical timing signal may be utilizedby the master and slave IC chips to initiate a capacitive frame. At step1020, the vertical timing signal and the horizontal timing signal aretransmitted to the slave IC chip from the master IC chip. For example,the horizontal timing and vertical timing signals may be transmittedfrom input/output pins on the master IC chip 340 to corresponding pinson the slave IC chip 350 and/or 360.

At step 1030, the master IC chip initiates acquisition of a firstcapacitive frame. In one embodiment, the master IC chip 340 initiatesacquisition of a first capacitive frame based on at least one a verticaltiming signal a horizontal timing signal. For example, the master ICchip 340 may initiate acquisition of the first capacitive frame bydetecting a rising edge of the vertical timing signal. The master ICchip may be configured to operate the sensor electrodes 205 b forabsolute capacitive sensing and/or transcapacitive sensing. For example,upon detection of a rising edge of the vertical timing signal, themaster IC chip 340 drives each of the sensor electrodes 205 b with anabsolute capacitive sensing signal.

At step 1040, the slave IC chip initiates acquisition of a secondcapacitive frame. In one embodiment, the slave IC chip 350, 360initiates acquisition of a second capacitive frame based on at least onethe vertical timing signal the horizontal timing signal provided by themaster IC chip 340. For example, the master IC chip 340 may communicatethe vertical and horizontal timing signals to the slave IC chip 350. Theslave IC chip receives vertical and horizontal timing signals andinitiates acquisition of the second capacitive frame by detecting arising edge of the vertical timing signal and driving a first one ormore of sensor electrodes 205 a with sensing signal 352 to operate thesensor electrodes 205 a for transcapacitive sensing and/or absolutecapacitive sensing. For example, upon detection of a rising edge of thevertical timing signal, the slave IC chip 350 drives each of the sensorelectrodes 205 a with an absolute capacitive sensing signal.

Method 1100 of FIG. 11 illustrates steps for synchronizing sensingsignals of two or more IC chips. At step 1110, the master IC chipgenerates a first delay and a second delay. The first delay correspondsto a signal propagation measurement within the master IC chip and thesecond delay corresponds to a signal propagation measurement between themaster IC chip and a slave IC chip. In one embodiment, the master ICchip transmits a first timing signal that is fed back into the master IC350 chip via loopback path and received by the waveform generator of themaster IC chip. The timing difference between when the timing signal istransmitted and then is received by the master IC chip 340 to determinethe first delay. In one embodiment, the master IC chip 340 may beconfigured to initiate a counter when the timing signal is transmittedand stop the counter when the timing signal is received. The value ofthe counter may correspond to the first delay.

The second delay may be measured by transmitting a timing signal fromthe master IC chip 340 to the slave IC chip 350 and then back to themaster IC chip 340. The difference in time from when the timing signalis transmitted from the master IC chip 340 and received by the master ICchip may be used to determine the second delay. In one embodiment, themaster IC chip 340 may be configured to initiate a counter when thetiming signal is transmitted to the slave IC chip and stop the counterwhen the timing signal is received.

At step 1120, the second delay is output from the master IC chip to theslave IC chip. For example, the second delay is output from the masterIC chip 340 to the slave IC chip 350.

At step 1130, a first sensing signal is generated by the master IC chip,based at least in part on the first delay. The first delay may be usedto delay when the first sensing signal 342 is output by the master ICchip 340 onto sensor electrodes 205 b. In one embodiment, the firstpulse of the first sensing signal 342 is delayed by the first delay.

At step 1140, a second sensing signal is generated by the slave IC chip,based at least in part on the second delay. The second delay may be usedto delay when the second sensing signal 352 is output by the slave ICchip 350. In one embodiment, the first pulse of the second sensingsignal 352 is delayed by the second delay, such that sensor electrodes205 a, and 205 b are driven at substantially the same time. For example,the difference in time between driving the sensor electrodes 205 a and205 b is less than about 50 ns,

FIG. 12 illustrates method 1200 for synchronizing sensing bursts betweentwo or more IC chips. At step 1210, the master IC chip initiates asensing burst of a first sensing signal based on the horizontal timingsignal. For example, master IC chip 340 is configured to detect a risingedge of the horizontal timing signal and generate a first burst ofsensing signal 342. The master IC chip 340 outputs the first sensingsignal onto one or more sensor electrodes 205 b.

At step 1220, the slave IC chip initiates a sensing burst of a secondsensing burst. For example, slave IC chip 350 is configured to detect arising edge of the horizontal timing signal and generate a first burstof sensing signal 352, and outputs the first sensing signal onto one ormore sensor electrodes 205 a. As the bursts of the first and secondsensing signal are both initiated based on the horizontal timing signalof the master IC chip 340, initiation of the first and second sensingsignals are synchronized.

Method 1300 of FIG. 13 illustrates a method for synchronizing a clocksignal of a master IC chip with the clock signal of a slave IC chip. Atstep 1310, a clock timing signal is output from the master IC chip to aslave IC chip. For example, master IC chip 340 may output the master ICchip's clock signal to the slave IC chip 350. At step 1320, the clocksignal of the slave IC chip is compared with the clock timing signal.For example, slave IC chip 350 may be configured to detect a firstrising edge of the clock timing signal and determine how many risingedges of the slave IC chip's clock signal occur before the falling edgeof the clock timing signal is detect.

At step 1330, the clock signal of the slave IC chip is changed based onthe comparison between the clock signal of the slave IC chip and theclock timing signal. For example, if the number of rising edges of theclock of the slave IC chip that occur between rising and falling edgesof the clock timing signal is determined to have changed, the clocksignal of the slave IC chip may be increased or decreased in frequency,respectively. For example, the frequency of the clock signal of theslave IC chip 350, 360 may be increased when the number of rising edgesof the clock signal of the slave IC chip 350, 360 has been determined tohave decreased. Alternatively, the frequency of the clock signal of theslave IC 350, 360 may be decreased when the number of rising edges ofthe clock signal of the slave IC chip 350, 360 has been determined tohave increased.

Thus, the embodiments and examples set forth herein were presented inorder to best explain the embodiments in accordance with the presenttechnology and its particular application and to thereby enable thoseskilled in the art to make and use the disclosure. However, thoseskilled in the art will recognize that the foregoing description andexamples have been presented for the purposes of illustration andexample only. The description as set forth is not intended to beexhaustive or to limit the disclosure to the precise form disclosed.

In view of the foregoing, the scope of the present disclosure isdetermined by the claims that follow.

What is claimed is:
 1. An input device comprising: a plurality of sensor electrodes; a master integrated circuit (IC) chip communicatively coupled to a plurality of sensor electrodes, the master IC chip configured to: generate a vertical timing signal and a horizontal timing signal; and initiate acquisition of a first capacitive frame based on at least one of the vertical timing signal and the horizontal timing signal by driving the plurality of sensor electrodes with a first sensing signal comprising one or more sensing bursts; and a first slave IC chip communicatively coupled with the master IC chip and to the plurality of sensor electrodes, the first slave IC chip is configured to: receive the vertical timing signal and the horizontal timing signal from the master IC chip; and initiate acquisition of a second capacitive frame based on at least one of the vertical timing signal and the horizontal timing signal by driving the plurality of sensor electrodes with a second sensing signal comprising one or more sensing bursts.
 2. The input device of claim 1, wherein the master IC chip is further configured to: generate a first delay and a second delay, the first delay corresponding to a signal propagation measurement within the master IC chip and the second delay corresponding to a signal propagation measurement between the master IC chip and the first slave IC chip; and output the second delay.
 3. The input device of claim 2, the master IC chip is further configured to: determine the signal propagation measurement within the master IC chip by measuring a time difference between outputting a first timing pulse and receiving the first timing pulse within the master IC chip; and determine the signal propagation measurement between the master IC chip and the first slave IC chip by measuring a time difference between outputting a second timing pulse to a first slave IC chip and receiving the second timing pulse from the first slave IC chip.
 4. The input device of claim 3, wherein the first delay is a function of the signal propagation measurement within the master IC chip.
 5. The input device of claim 2, wherein: the master IC chip is further configured to generate the first sensing signal having a plurality of pulses based at least in part on the first delay, and the first slave IC chip is further configured to: receive the second delay from the master IC chip; and generate the second sensing signal having a plurality of pulses based at least in part on the second delay.
 6. The input device of claim 1, wherein: the master IC chip is further configured to initiate at least one of the sensing bursts of the first sensing signal based on the horizontal timing signal, and the first slave IC chip is further configured to initiate at least one of the sensing bursts of the second sensing signal based on the horizontal timing signal.
 7. The input device of claim 1, wherein: the master IC chip is further configured to output a clock timing signal, and the first slave IC chip is further configured to: receive the clock timing signal; compare a clock signal of the first slave IC chip to the clock timing signal; and change the clock signal of the first slave IC chip based on the comparison.
 8. The input device of claim 1 further comprising: a second slave IC chip communicatively coupled with the master IC chip and to the plurality of sensor electrodes, the first slave IC is configured to: receive the vertical timing signal and the horizontal timing signal from the master IC chip; and initiate acquisition of a third capacitive frame based on at least one of the vertical timing signal and the horizontal timing signal, wherein acquiring the third capacitive frame comprises driving the plurality of sensor electrodes with a third sensing signal comprising one or more sensing bursts.
 9. The input device of claim 8, wherein the first slave IC chip and the second slave IC chips are disposed on different sides of the master IC chip.
 10. The input device of claim 1, wherein each of the plurality of sensor electrodes comprise at least one display electrode of a plurality of display electrodes of a display device, and wherein master IC chip and the slave IC chip are configured to drive the plurality of display electrodes to update the display device.
 11. The input device of claim 1, wherein driving the plurality of sensor electrodes by the master IC chip comprises driving a first portion of the plurality of sensor electrodes, and wherein driving the plurality of sensor electrodes by the first slave IC chip comprises driving a second portion of the plurality of sensor electrodes.
 12. A method for synchronizing integrated circuit (IC) chips, the method comprising: generating, with a master IC chip, a vertical timing signal and a horizontal timing signal; transmitting the vertical timing signal and the horizontal timing signal from the master IC chip to a slave IC chip; initiating acquisition of first sensing measurements by the master IC chip based on at least one of the vertical timing signal and the horizontal timing signal; and initiating acquisition of second sensing measurements by the slave IC chip based on at least one of the vertical timing signal and the horizontal timing signal.
 13. The method of claim 12 further comprising: generating, by the master IC chip, a first delay and a second delay, the first delay corresponding to a signal propagation measurement within the master IC chip and the second delay corresponding to a signal propagation measurement between the master IC chip and the slave IC chip; outputting the second delay from the master IC chip to the slave IC chip; generating, by the master IC chip, a first sensing signal at least in part on the first delay, wherein the first sensing signal is used to drive one or more sensor electrodes; and generating, by the slave IC chip, a second sensing signal based at least in part on the second delay, wherein the second sensing signal is used to drive one or more sensor electrodes.
 14. The method of claim 13 further comprising: determining, by the master IC chip, the signal propagation measurement within the master IC chip by measuring a time difference between outputting a first timing pulse and receiving the first timing pulse within the master IC chip; and determining, by the master IC chip, the signal propagation measurement between the master IC chip and the slave IC chip by measuring a time difference between outputting a second timing pulse to a first slave IC chip and receiving the second timing pulse from the first slave IC chip.
 15. The method of claim 13 further comprising: initiating, by the master IC chip, at least one sensing burst of the first sensing signal based on the horizontal timing signal; and initiating, by the slave IC chip, at least one sensing burst of the second sensing signal based on the horizontal timing signal.
 16. The method of claim 12 further comprising: outputting a clock timing signal from the master IC chip to the slave IC chip; and comparing a clock signal of the slave IC chip to the clock timing signal; and changing the clock signal of the slave IC chip based at least in part on the comparison.
 17. A processing system for a display device having an integrated capacitive sensing device, the processing system comprising: a master integrated circuit (IC) chip communicatively coupled to a plurality of sensor electrodes, the master IC chip configured to: generate a vertical timing signal and a horizontal timing signal; initiate acquisition of a first capacitive frame based on at least one of the vertical timing signal and the horizontal timing signal by driving the plurality of sensor electrodes with a first sensing signal corresponding to one or more sensing bursts; and a slave IC chip communicatively coupled with the master IC chip and to the plurality of sensor electrodes, the slave IC chip is configured to: receive the vertical timing signal and the horizontal timing signal from the master IC chip; and initiate acquisition of a second capacitive frame based on at least one of the vertical timing signal and the horizontal timing signal by driving the plurality of sensor electrodes with a second sensing signal corresponding to one or more sensing bursts.
 18. The processing system of claim 17, wherein the master IC chip is further configured to: determine a signal propagation measurement within the master IC chip by measuring a time difference between outputting a first timing pulse and receiving the first timing pulse within the master IC chip; determine a signal propagation measurement between the master IC chip and the slave IC chip by measuring a time difference between outputting a second timing pulse to a first slave IC chip and receiving the second timing pulse from the slave IC chip; and generate a first delay based at least one the signal propagation measurement within the master IC chip and the signal propagation measurement between the master IC chip and the slave IC chip; generate a second delay based at least one the signal propagation measurement between the master IC chip and the first slave IC chip; and output the second delay.
 19. The processing system of claim 18, wherein: the master IC chip is further configured to: generate the first sensing signal based at least in part on the first delay, and the slave IC chip is further configured to: receive the second delay from the master IC chip; and generate the second sensing signal based at least in part on the second delay.
 20. The processing system of claim 17, wherein: the master IC chip is further configured to: initiate at least one of the plurality of sensing bursts of the first sensing signal based on the horizontal timing signal, and the slave IC chip is further configured to initiate at least one of the plurality of sensing bursts of the second sensing signal based on the horizontal timing signal.
 21. The processing system of claim 17, wherein: the master IC chip is further configured to: output a clock timing signal, and the slave IC chip is further configured to: receive the clock timing signal; compare a clock signal of the slave IC chip to the clock timing signal; and change the clock signal of the slave IC chip based on the comparison.
 22. The processing system of claim 17, wherein driving the plurality of sensor electrodes by the master IC chip comprises driving a first portion of the plurality of sensor electrodes, and wherein driving the plurality of sensor electrodes by the first slave IC chip comprises driving a second portion of the plurality of sensor electrodes. 